Thursday, 17 August 2006

So What Are These Liquid Explosives?

by CKR

My curiosity is piqued. I hadn’t paid much attention to this business of liquid explosives until last week. Nitroglycerin, yes, is an explosive liquid. But which are the exciting compounds are that are odorless and inert by themselves and detonate when mixed?

After googling a few pages of links to uninformative news stories, QandO reminds me of GlobalSecurity.org, who list some liquid and sort-of-liquid explosives, although the article lapses back into a discussion of cartridged explosives, which are solid or at least pasty or gels. None of these liquids or mixtures, however, fit the sensational news descriptions of inert compounds that magically detonate when mixed.
Nitroglycerin. Very sensitive. Already said that.
Astrolite, a mixture of ammonium nitrate and anhydrous hydrazine
Nitromethane with a sensitizerKinepak, a mixture of ammonium nitrate and nitromethane
Binex, a mixture of a sodium perchlorate solution and aluminum powder.

Ammonium nitrate is grass fertilizer. It's a solid. It can be mixed with things like fuel oil to make explosives, as was done for the Oklahoma City bombing. It can explode by itself, too. The enormous Texas City explosion of 1947 was of a shipload of ammonium nitrate. Apparently anhydrous hydrazine can dissolve it to form a liquid that is called Astrolite. Anhydrous hydrazine is also known as rocket fuel and is considered an explosive itself. Anhydrous means that it doesn’t have any water in it, and that adjective is usually applied to substances that pick up water easily. You’ve seen how sugary things can sort of melt on a humid day. The sugar is dissolving itself in water pulled from the air by chemical attraction. Hydrazine picks up water that way too. It’s a poison and is hard to buy, unless you’re NASA.

Nitromethane is easier to buy. It’s used in model airplane engines and drag racers. It’s extremely flammable. The sensitizers are amines and other things that are hard to buy. Since nitromethane is more energetic than fuel oil, ammonium nitrate can be combined with it in the same way to produce an explosive that is a paste or moist powder, not a liquid. The two components don’t have to be stored as explosives, which simplifies things for commercial handlers. We’re talking about regulations, having the proper signs and transporting and storing them in the proper ways. Terrorists don’t care about that. Nitromethane is a liquid, but ammonium nitrate is a solid, and the mixture is a paste or moist powder.

For Binex, the sodium perchlorate solution is a liquid, and powdered aluminum is a solid. Seems to me because the aluminum would fall to the bottom of the solution. I don’t know whether this would make a difference to its explosive qualities, but I suspect it would. So a gel or suspension would be necessary. Most of the gelling agents are organics, though, and I’m wondering if they wouldn’t react with the perchlorate prematurely.

So how do all these stack up against the sensational claims in the media?

None are two liquids that detonate when mixed together.

The only ones that are liquids are nitroglycerin, Astrolite, and sensitized nitromethane. You can’t get anhydrous hydrazine for Astrolite on the open market, and even if you could, it’s very, very hard to handle. The nitromethane sensitizers are difficult to obtain.

The GlobalSecurity.org article is confusing, but I think it says that all the mixtures need a blasting cap to set them off. This is more than the electrical detonators described in the media; a blasting cap has an electrical detonator attached to a primary (sensitive) explosive. It is the primary explosive that then sets off the main charge. We can hope that the TSA x-ray readers know what a blasting cap looks like.

Most of these components are pretty stinky, far from odorless. The perchlorate solution with aluminum would come closest to odorless. The odor of the amines for sensitizing nitromethane starts from dead fish and gets worse. It really doesn’t come off your hands, either.

There’s also a question of how much is needed. Nitroglycerin is one of the more powerful explosives in this group. A Russian expert estimates that one to one and a half kilograms of nitroglycerin would be necessary to bring down an airliner. Nitroglycerin is much denser than water, so that amounts to between one and two. Gatorade bottles would indeed be required for something like that, hardly those little tubes of hand cream some of us carry in our purses and for which a transatlantic flight was diverted yesterday.

Bottom line: There are a few more liquid explosives in addition to nitroglycerin, but the scenarios we’re hearing from the media would be very, very hard to carry off, some impossible. Unless there’s still more kinds of liquid explosive out there, and, oh yes, all those things that the government can’t tell us, but the terrorists know…

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So What Are These Liquid Explosives?

by CKR

My curiosity is piqued. I hadn’t paid much attention to this business of liquid explosives until last week. Nitroglycerin, yes, is an explosive liquid. But which are the exciting compounds are that are odorless and inert by themselves and detonate when mixed?

After googling a few pages of links to uninformative news stories, QandO reminds me of GlobalSecurity.org, who list some liquid and sort-of-liquid explosives, although the article lapses back into a discussion of cartridged explosives, which are solid or at least pasty or gels. None of these liquids or mixtures, however, fit the sensational news descriptions of inert compounds that magically detonate when mixed.
Nitroglycerin. Very sensitive. Already said that.
Astrolite, a mixture of ammonium nitrate and anhydrous hydrazine
Nitromethane with a sensitizerKinepak, a mixture of ammonium nitrate and nitromethane
Binex, a mixture of a sodium perchlorate solution and aluminum powder.